The pilot made a bad decision and was flying special visual flight rules when he should have been on an instrument flight plan, and it cost everyone their lives. Having a lot of military flight time, I've definitely had to push bad weather trying to get underneath clouds for mission essential stuff. One of those times it bit me in the ass and I accidentally went into the clouds. Going into the clouds when you're not expecting it is bad enough with an instrument rating, but for someone that is not qualified, it almost guarantees death due to vertigo and then controlled flight into terrain. Fortunately I have an instrument rating and a good amount of hours. Often times these charter pilots don't have that. This is just as likely to happen to a plane as it is a helo, btw.
P.S. Autorotations are fun